strip_unknown_attributes.cpp

/*
 * Copyright 2013, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "strip_unknown_attributes.h"

namespace slang {

StripUnknownAttributes::StripUnknownAttributes() : ModulePass(ID) {
}


bool StripUnknownAttributes::runOnFunction(llvm::Function &F) {
  bool changed = false;
  for (llvm::Function::arg_iterator I = F.arg_begin(), E = F.arg_end();
       I != E; ++I) {
    llvm::Argument &A = *I;
    // Remove any readnone/readonly attributes from function parameters.
    if (A.onlyReadsMemory()) {
      llvm::AttrBuilder B;
      B.addAttribute(llvm::Attribute::ReadNone);
      B.addAttribute(llvm::Attribute::ReadOnly);
      llvm::AttributeSet ToStrip = llvm::AttributeSet::get(F.getContext(),
          A.getArgNo() + 1, B);
      A.removeAttr(ToStrip);
      changed = true;
    }
  }
  return changed;
}


bool StripUnknownAttributes::runOnModule(llvm::Module &M) {
  bool Changed = false;
  for (llvm::Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
    Changed |= runOnFunction(*I);
  }
  return Changed;
}


llvm::ModulePass * createStripUnknownAttributesPass() {
  return new StripUnknownAttributes();
}


char StripUnknownAttributes::ID = 0;
static llvm::RegisterPass<StripUnknownAttributes> RPSUA(
    "StripUnknownAttributes", "Strip Unknown Attributes Pass");

}  // namespace slang